In fabricating membrane modules maximizing the contacting efficiency is of tremendous importance. Contacting efficiency is a function of fluid dynamics and this is particularly true in concentration gradient driven processes (perstraction and pervaporation applications) and in pressure driven processes (reverse osmosis and ultrafiltration).
Current permeator designs suffer from contacting efficiency limitations. Spiral wound, tubular membrane, flat sheet, and hollow fiber modules all exhibit contacting efficiency limitations and attempt to address the limitations in various ways, including the use of flow direction blocks, turbulence promoters on the surface of the membrane, specially designed feed/retentate spacers, anti-channeling wraps etc. Absent such expedients the contacting efficiency limitations are compensated for by employing more or larger modules so as to provide more effective surface area.
Contacting efficiency limitations cannot be tolerated where separation efficiency targets are high or where large volumes of materials are to be handled. Providing additional surface area to compensate for inefficient contacting is not an acceptable solution in those cases.
The present invention presents a permeator design criterion which significantly reduces contacting efficiency limitation problems, especially for hollow fiber modules, without adding more surface area.